The present invention relates to therapeutic toothpastes having improved cleaning and abrasion performance attributed to a low foam characteristic and the absence of substantial surfactant bubble interference with the abrasive/tooth surface interface during brushing. As a result of this improved cleaning and abrasion, the therapeutic activity of each of these low foaming toothpastes is generally improved.
In the oral hygiene field today, toothbrushing is generally carried out with a toothbrush/toothpaste combination where the abrasive in the toothpaste is brought into contact with tooth surfaces by the bristles of the toothbrush. The leading commercial toothpastes presently marketed are characterized by a controlled foam profile, resulting in foam initially filling a good part of the oral cavity, eventually dissipating at the end of the brushing cycle, such that the residue can be conveniently expectorated.
Examples of therapeutic toothpastes include "fluoride", "anti-tartar", "anti-plaque", "baking soda", "anti-gingivitis", and "hypersensitivity treatment" toothpastes, some of which are described in the following U.S. Pat. Nos. 4,254,101; 4,515,772; 4,684,518; 4,806,339; 4,806,340; 4,842,165; 4,885,155; 4,889,712; 4,891,211; 4,999,184; 5,004,597; 5,180,576; 5,374,368; and 5,424,060. These patents are to be incorporated by reference in the present specification. The toothpastes described in these patents generally use one or more abrasive substances to abrasively clean, polish and remove stains, plaque and tartar from the surfaces of teeth in preparation for imparting various therapeutic benefits to the oral cavity.
The current level of gum disease and tooth loss attributed to gum disease and gum retraction in adults, along with high incidence of gingivitis, coronal caries and hypersensitivity among adults, suggests the referenced toothpastes may not be cleaning as efficiently as one would hope they would and therefore not imparting the optimum therapeutic benefits intended.
During toothbrushing, the primary function of the toothbrush bristles is to rub abrasive particles contained in the toothpaste across the surfaces of the teeth, thereby removing by abrasive action tooth deposits such as pellicle, stains, plaque, tartar and the like while delivering various active ingredients such as fluoride, anti-tartar, anti-gingivitis ingredients, etc. to the "cleaned" oral cavity.
Studies show that the most aggressive mechanical cleansing with a toothpaste/toothbrush combination should be directed toward the tooth surface, with much less so toward the gingival surface and essentially none toward the base of the gingival sulcus. The basis for these observations is as follows:
1. The development of gingival inflammation and dental caries is most frequently caused by failure to remove dental plaque from the subgingival surface of the tooth and to a much lesser extent materia alba from the gingival surface in the subgingival space. Both dental plaque and materia alba can form within several hours of brushing and therefore frequent mechanical cleansing is essential. Materia alba which consists primarily of an acquired bacterial coating and desquamated epithelial cells, leukocytes and a mixture of salivary proteins and lipids is a soft sticky deposit less adherent than dental plaque. It can be flushed away with a water spray but more completely removed from the gingiva with a mild mechanical cleansing. PA1 2. Dental plaque is formed by oral microorganisms that synthesize harmful products that are destructive to the tooth and gums when not removed from the gingival sulcus. The toxins formed by these microorganisms cause cellular damage to the gingiva with subsequent inflammation (gingivitis) and eventually destruction of the supporting structures (periodontitis). When gingivitis occurs, vascular dilation, capillary proliferation, engorged vessels and sluggish venous return causes a stretched and thinned epithelium that is sensitive to mechanical trauma such as aggressive brushing. PA1 3. Dental plaque with associated gingivitis also causes exposure of the root surface (recession) with increased occurrence of cavities (dental caries). Exposure of the root surfaces can also occur due to faulty brushing by repeated direct trauma to the base of the sulcus (gingival abrasion). When a pathologically deepened gingival sulcus (periodontal pocket) occurs, the pathological condition may become exacerbated because plaque can more readily occur. If dental plaque is not removed, calculus (tartar) is formed by mineralization of the bacterial plaque. Calculus can form within several hours of plaque formation. Calculus has a bacterial plaque coating and exacerbates gingivitis and gingival recession by both chemical irritation from the formed toxins and destruction from the mechanical irritation of the calculus mass. Subgingival calculus usually extends near but does not reach the base of periodontal pockets in chronic periodontal lesions. Calculus holds the plaque against gingiva, and PA1 4. Since materia alba can be removed by light mechanical cleansing and gingival inflammation causes thinning of the gingival epithelium the mechanical cleansing requirement of the gingival surface is much less than the requirement for removing dental plaque from the surface of the teeth.
Accordingly, a more efficient cleansing and abrading therapeutic toothpaste that fulfills the foregoing requirements, and is more effective therapeutically, is desirable.
In order for the abrasives used in toothpastes today to approach optimum cleaning abrasion performance, channeled bristle toothbrushes have been developed to entrap the abrasive and extend abrasive/toothbrush contact beyond tangential contact between bristle tips/abrasive with tooth surfaces. Preferred brushes of this type are described in U.S. application Ser. No. 08/899,679, Attorney Docket No. 1648/46640, filed on even date herewith. The contents of said application are hereby incorporated herein by reference.
In addition to the entrapment of toothpaste abrasive in the channeled bristles, improved toothpaste cleaning efficiency and improved toothpaste abrasion efficiency requires that the abrasive particles entrapped in these bristle channels be brought into direct contact without bubble interference with those tooth surfaces requiring cleaning, polishing, stain removal, etc. This contact is most effective when the bubbles produced by surfactants are minimal and preferably excluded from the abrasive/tooth surface interference.
The use of high foaming surfactants in toothpastes as taught in the referenced patents of market leading toothpastes such as Crest.RTM., Colgate.RTM., Arm & Hammer.RTM. . . . although creating the consumer "impression of cleaning" in fact interferes with abrasive packing in bristle channels and with the abrasive/tooth surface contacts required, for optimum cleaning and abrasion performance, similar to the way high foaming detergents interfere with soil removal. Eventually, high foaming detergents gave way to the more efficient low foaming detergents and today have been totally replaced in the laundry market by low foaming (low sudsing) detergents.
The advent of abrasive entrapping toothbrush bristles calls for the use of low foaming surfactants in toothpastes in order to optimize abrasive "packing" in the toothbrush bristles and to optimize abrasive/tooth surface contact during toothbrushing, thereby optimizing toothpaste cleaning and abrasion efficiencies.
Surfactant "bubble" interference with entrapped abrasive/tooth surface contact is illustrated in FIG. 1 of the drawings and is contrasted with substantial bubble free entrapped abrasive/tooth surface contact as is illustrated in FIG. 3. Bubble interference with abrasive packing illustrated in FIG. 2 is contrasted with FIG. 4, which illustrates bubble free abrasive packing in the bristle channel.